UnrealEngineUWP/Engine/Source/Runtime/RenderCore/Private/ShaderParameterMetadata.cpp

// Copyright Epic Games, Inc. All Rights Reserved.

/*=============================================================================
	ShaderParameterMetadata.cpp: Shader parameter metadata implementations.
=============================================================================*/

#include "ShaderParameterMetadata.h"
#include "RenderCore.h"
#include "ShaderCore.h"

FUniformBufferStaticSlotRegistrar::FUniformBufferStaticSlotRegistrar(const TCHAR* InName)
{
	FUniformBufferStaticSlotRegistry::Get().RegisterSlot(InName);
}

FUniformBufferStaticSlotRegistry& FUniformBufferStaticSlotRegistry::Get()
{
	static FUniformBufferStaticSlotRegistry Registry;
	return Registry;
}

void FUniformBufferStaticSlotRegistry::RegisterSlot(FName SlotName)
{
	// Multiple definitions with the same name resolve to the same slot.
	const FUniformBufferStaticSlot Slot = FindSlotByName(SlotName);

	if (!IsUniformBufferStaticSlotValid(Slot))
	{
		SlotNames.Emplace(SlotName);
	}
}

#define VALIDATE_UNIFORM_BUFFER_UNIQUE_NAME (!UE_BUILD_SHIPPING && !UE_BUILD_TEST)

#if VALIDATE_UNIFORM_BUFFER_UNIQUE_NAME
TMap<FName, FName> & GetGlobalShaderVariableToStructMap()
{
	static TMap<FName, FName> GlobalShaderVariableToStructMap;
	return GlobalShaderVariableToStructMap;
}
#endif

TMap<uint32, FShaderParametersMetadata*> & GetLayoutHashStructMap()
{
	static TMap<uint32, FShaderParametersMetadata*> GLayoutHashStructMap;
	return GLayoutHashStructMap;
}

TLinkedList<FShaderParametersMetadata*>*& FShaderParametersMetadata::GetStructList()
{
	static TLinkedList<FShaderParametersMetadata*>* GUniformStructList = nullptr;
	return GUniformStructList;
}

TMap<FHashedName, FShaderParametersMetadata*>& FShaderParametersMetadata::GetNameStructMap()
{
	static TMap<FHashedName, FShaderParametersMetadata*> NameStructMap;
	return NameStructMap;
}

void FShaderParametersMetadata::FMember::GenerateShaderParameterType(FString& Result, bool bSupportsPrecisionModifier) const
{
	switch (GetBaseType())
	{
	case UBMT_INT32:   Result = TEXT("int"); break;
	case UBMT_UINT32:  Result = TEXT("uint"); break;
	case UBMT_FLOAT32:
		if (GetPrecision() == EShaderPrecisionModifier::Float || !bSupportsPrecisionModifier)
		{
			Result = TEXT("float");
		}
		else if (GetPrecision() == EShaderPrecisionModifier::Half)
		{
			Result = TEXT("half");
		}
		else if (GetPrecision() == EShaderPrecisionModifier::Fixed)
		{
			Result = TEXT("fixed");
		}
		break;
	default:
		UE_LOG(LogShaders, Fatal, TEXT("Unrecognized uniform buffer struct member base type."));
	};

	// Generate the type dimensions for vectors and matrices.
	if (GetNumRows() > 1)
	{
		Result = FString::Printf(TEXT("%s%ux%u"), *Result, GetNumRows(), GetNumColumns());
	}
	else if (GetNumColumns() > 1)
	{
		Result = FString::Printf(TEXT("%s%u"), *Result, GetNumColumns());
	}
}

void FShaderParametersMetadata::FMember::GenerateShaderParameterType(FString& Result, EShaderPlatform ShaderPlatform) const
{
	GenerateShaderParameterType(Result, SupportShaderPrecisionModifier(ShaderPlatform));
}

FShaderParametersMetadata* FindUniformBufferStructByName(const TCHAR* StructName)
{
	return FindUniformBufferStructByFName(FName(StructName, FNAME_Find));
}

FShaderParametersMetadata* FindUniformBufferStructByFName(FName StructName)
{
	return FShaderParametersMetadata::GetNameStructMap().FindRef(StructName);
}

FShaderParametersMetadata* FindUniformBufferStructByLayoutHash(uint32 Hash)
{
	return GetLayoutHashStructMap().FindRef(Hash);
}

const TCHAR* const kShaderParameterMacroNames[] = {
	TEXT(""), // UBMT_INVALID,

	// Invalid type when trying to use bool, to have explicit error message to programmer on why
	// they shouldn't use bool in shader parameter structures.
	TEXT("SHADER_PARAMETER"), // UBMT_BOOL,

	// Parameter types.
	TEXT("SHADER_PARAMETER"), // UBMT_INT32,
	TEXT("SHADER_PARAMETER"), // UBMT_UINT32,
	TEXT("SHADER_PARAMETER"), // UBMT_FLOAT32,

	// RHI resources not tracked by render graph.
	TEXT("SHADER_PARAMETER_TEXTURE"), // UBMT_TEXTURE,
	TEXT("SHADER_PARAMETER_SRV"), // UBMT_SRV,
	TEXT("SHADER_PARAMETER_UAV"), // UBMT_UAV,
	TEXT("SHADER_PARAMETER_SAMPLER"), // UBMT_SAMPLER,

	// Resources tracked by render graph.
	TEXT("SHADER_PARAMETER_RDG_TEXTURE"), // UBMT_RDG_TEXTURE,
	TEXT("RDG_TEXTURE_ACCESS"), // UBMT_RDG_TEXTURE_ACCESS,
	TEXT("RDG_TEXTURE_ACCESS_ARRAY"), // UBMT_RDG_TEXTURE_ACCESS,
	TEXT("SHADER_PARAMETER_RDG_TEXTURE_SRV"), // UBMT_RDG_TEXTURE_SRV,
	TEXT("SHADER_PARAMETER_RDG_TEXTURE_UAV"), // UBMT_RDG_TEXTURE_UAV,
	TEXT("RDG_BUFFER_ACCESS"), // UBMT_RDG_BUFFER_ACCESS,
	TEXT("RDG_BUFFER_ACCESS_ARRAY"), // UBMT_RDG_BUFFER_ACCESS_ARRAY,
	TEXT("SHADER_PARAMETER_RDG_BUFFER_SRV"), // UBMT_RDG_BUFFER_SRV,
	TEXT("SHADER_PARAMETER_RDG_BUFFER_UAV"), // UBMT_RDG_BUFFER_UAV,
	TEXT("SHADER_PARAMETER_RDG_UNIFORM_BUFFER"), // UBMT_RDG_UNIFORM_BUFFER,

	// Nested structure.
	TEXT("SHADER_PARAMETER_STRUCT"), // UBMT_NESTED_STRUCT,

	// Structure that is nested on C++ side, but included on shader side.
	TEXT("SHADER_PARAMETER_STRUCT_INCLUDE"), // UBMT_INCLUDED_STRUCT,

	// GPU Indirection reference of struct, like is currently named Uniform buffer.
	TEXT("SHADER_PARAMETER_STRUCT_REF"), // UBMT_REFERENCED_STRUCT,

	// Structure dedicated to setup render targets for a rasterizer pass.
	TEXT("RENDER_TARGET_BINDING_SLOTS"), // UBMT_RENDER_TARGET_BINDING_SLOTS,
};

static_assert(UE_ARRAY_COUNT(kShaderParameterMacroNames) == int32(EUniformBufferBaseType_Num), "Shader parameter enum does not match name macro name array.");

/** Returns the name of the macro that should be used for a given shader parameter base type. */
const TCHAR* GetShaderParameterMacroName(EUniformBufferBaseType ShaderParameterBaseType)
{
	check(ShaderParameterBaseType != UBMT_INVALID);
	return kShaderParameterMacroNames[int32(ShaderParameterBaseType)];
}

EShaderCodeResourceBindingType ParseShaderResourceBindingType(const TCHAR* ShaderType)
{
	const bool bIsRasterizerOrderedResource = FCString::Strncmp(ShaderType, TEXT("RasterizerOrdered"), 17) == 0;
	const bool bIsRWResource = FCString::Strncmp(ShaderType, TEXT("RW"), 2) == 0 || bIsRasterizerOrderedResource;
	const TCHAR* ComparedShaderType = ShaderType + (bIsRWResource ? 2 : 0);

	int32 ShaderTypeLength = 0;
	while (TCHAR c = ComparedShaderType[ShaderTypeLength])
	{
		if (c == ' ' || c == '<')
			break;
		ShaderTypeLength++;
	}

	EShaderCodeResourceBindingType BindingType = EShaderCodeResourceBindingType::Invalid;
	if (!bIsRWResource && ShaderTypeLength == 12 && FCString::Strncmp(ComparedShaderType, TEXT("SamplerState"), ShaderTypeLength) == 0)
	{
		BindingType = EShaderCodeResourceBindingType::SamplerState;
	}
	else if (!bIsRWResource && ShaderTypeLength == 22 && FCString::Strncmp(ComparedShaderType, TEXT("SamplerComparisonState"), ShaderTypeLength) == 0)
	{
		BindingType = EShaderCodeResourceBindingType::SamplerState;
	}
	else if (ShaderTypeLength == 9 && FCString::Strncmp(ComparedShaderType, TEXT("Texture2D"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWTexture2D : EShaderCodeResourceBindingType::Texture2D;
	}
	else if (ShaderTypeLength == 15 && FCString::Strncmp(ComparedShaderType, TEXT("TextureExternal"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWTexture2D : EShaderCodeResourceBindingType::Texture2D;
	}
	else if (ShaderTypeLength == 14 && FCString::Strncmp(ComparedShaderType, TEXT("Texture2DArray"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWTexture2DArray : EShaderCodeResourceBindingType::Texture2DArray;
	}
	else if (!bIsRWResource && ShaderTypeLength == 11 && FCString::Strncmp(ComparedShaderType, TEXT("Texture2DMS"), ShaderTypeLength) == 0)
	{
		BindingType = EShaderCodeResourceBindingType::Texture2DMS;
	}
	else if (ShaderTypeLength == 9 && FCString::Strncmp(ComparedShaderType, TEXT("Texture3D"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWTexture3D : EShaderCodeResourceBindingType::Texture3D;
	}
	else if (ShaderTypeLength == 11 && FCString::Strncmp(ComparedShaderType, TEXT("TextureCube"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWTextureCube : EShaderCodeResourceBindingType::TextureCube;
	}
	else if (!bIsRWResource && ShaderTypeLength == 16 && FCString::Strncmp(ComparedShaderType, TEXT("TextureCubeArray"), ShaderTypeLength) == 0)
	{
		BindingType = EShaderCodeResourceBindingType::TextureCubeArray;
	}
	else if (ShaderTypeLength == 15 && FCString::Strncmp(ComparedShaderType, TEXT("TextureMetadata"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWTextureMetadata : EShaderCodeResourceBindingType::TextureMetadata;
	}
	else if (ShaderTypeLength == 6 && FCString::Strncmp(ComparedShaderType, TEXT("Buffer"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWBuffer : EShaderCodeResourceBindingType::Buffer;
	}
	else if (ShaderTypeLength == 16 && FCString::Strncmp(ComparedShaderType, TEXT("StructuredBuffer"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWStructuredBuffer : EShaderCodeResourceBindingType::StructuredBuffer;
	}
	else if (ShaderTypeLength == 17 && FCString::Strncmp(ComparedShaderType, TEXT("ByteAddressBuffer"), ShaderTypeLength) == 0)
	{
		BindingType = bIsRWResource ? EShaderCodeResourceBindingType::RWByteAddressBuffer : EShaderCodeResourceBindingType::ByteAddressBuffer;
	}
	else if (!bIsRWResource && ShaderTypeLength == 31 && FCString::Strncmp(ComparedShaderType, TEXT("RaytracingAccelerationStructure"), ShaderTypeLength) == 0)
	{
		BindingType = EShaderCodeResourceBindingType::RaytracingAccelerationStructure;
	}
	else if (bIsRasterizerOrderedResource)
	{
		BindingType = EShaderCodeResourceBindingType::RasterizerOrderedTexture2D;
	}
	return BindingType;
}

const TCHAR* const kShaderCodeResourceBindingTypeNames[] = {
	TEXT("Invalid"),
	TEXT("SamplerState"),
	TEXT("Texture2D"),
	TEXT("Texture2DArray"),
	TEXT("Texture2DMS"),
	TEXT("Texture3D"),
	TEXT("TextureCube"),
	TEXT("TextureCubeArray"),
	TEXT("TextureMetadata"),
	TEXT("Buffer"),
	TEXT("StructuredBuffer"),
	TEXT("ByteAddressBuffer"),
	TEXT("RaytracingAccelerationStructure"),
	TEXT("RWTexture2D"),
	TEXT("RWTexture2DArray"),
	TEXT("RWTexture3D"),
	TEXT("RWTextureCube"),
	TEXT("RWTextureMetadata"),
	TEXT("RWBuffer"),
	TEXT("RWStructuredBuffer"),
	TEXT("RWByteAddressBuffer"),
	TEXT("RasterizerOrderedTexture2D"),
};

static_assert(UE_ARRAY_COUNT(kShaderCodeResourceBindingTypeNames) == int32(EShaderCodeResourceBindingType::MAX), "TODO.");

const TCHAR* GetShaderCodeResourceBindingTypeName(EShaderCodeResourceBindingType BindingType)
{
	check(BindingType != EShaderCodeResourceBindingType::Invalid);
	check(int32(BindingType) < int32(EShaderCodeResourceBindingType::MAX));
	return kShaderCodeResourceBindingTypeNames[int32(BindingType)];
}

class FUniformBufferMemberAndOffset
{
public:
	FUniformBufferMemberAndOffset(const FShaderParametersMetadata& InContainingStruct, const FShaderParametersMetadata::FMember& InMember, int32 InStructOffset) :
		ContainingStruct(InContainingStruct),
		Member(InMember),
		StructOffset(InStructOffset)
	{}

	const FShaderParametersMetadata& ContainingStruct;
	const FShaderParametersMetadata::FMember& Member;
	int32 StructOffset;
};

FShaderParametersMetadata::FShaderParametersMetadata(
	EUseCase InUseCase,
	EUniformBufferBindingFlags InBindingFlags,
	const TCHAR* InLayoutName,
	const TCHAR* InStructTypeName,
	const TCHAR* InShaderVariableName,
	const TCHAR* InStaticSlotName,
	const ANSICHAR* InFileName,
	const int32 InFileLine,
	uint32 InSize,
	const TArray<FMember>& InMembers,
	bool bForceCompleteInitialization,
	FRHIUniformBufferLayoutInitializer* OutLayoutInitializer,
	uint32 InUsageFlags)
	: LayoutName(InLayoutName)
	, StructTypeName(InStructTypeName)
	, ShaderVariableName(InShaderVariableName)
	, StaticSlotName(InStaticSlotName)
	, ShaderVariableHashedName(InShaderVariableName)
	, FileName(InFileName)
	, FileLine(InFileLine)
	, Size(InSize)
	, UseCase(InUseCase)
	, BindingFlags(InBindingFlags)
	, Members(InMembers)
	, GlobalListLink(this)
	, UsageFlags(InUsageFlags)
{
	checkf(UseCase == EUseCase::UniformBuffer || !EnumHasAnyFlags(BindingFlags, EUniformBufferBindingFlags::Static), TEXT("Only uniform buffers can utilize the global binding flag."));

	check(StructTypeName);
	if (UseCase == EUseCase::ShaderParameterStruct)
	{
		checkf(!StaticSlotName, TEXT("Only uniform buffers can be tagged with a static slot."));

		check(ShaderVariableName == nullptr);
	}
	else
	{
		check(ShaderVariableName);
	}
	
	// must ensure the global classes are full initialized before us
	//	so that they destruct after us
	#if VALIDATE_UNIFORM_BUFFER_UNIQUE_NAME
	GetGlobalShaderVariableToStructMap();
	#endif
	GetLayoutHashStructMap();
	GetStructList();
	GetNameStructMap();

	if (UseCase == EUseCase::UniformBuffer && !bForceCompleteInitialization)
	{
		// Register this uniform buffer struct in global list.
		GlobalListLink.LinkHead(GetStructList());

		FName StructTypeFName(StructTypeName);
		// Verify that during FName creation there's no case conversion
		checkSlow(FCString::Strcmp(StructTypeName, *StructTypeFName.GetPlainNameString()) == 0);
		GetNameStructMap().Add(ShaderVariableHashedName, this);


#if VALIDATE_UNIFORM_BUFFER_UNIQUE_NAME
		FName ShaderVariableFName(ShaderVariableName);

		// Verify that the global variable name is unique so that we can disambiguate when reflecting from shader source.
		if (FName* StructFName = GetGlobalShaderVariableToStructMap().Find(ShaderVariableFName))
		{
			checkf(
				false,
				TEXT("Found duplicate Uniform Buffer shader variable name %s defined by struct %s. Previous definition ")
				TEXT("found on struct %s. Uniform buffer shader names must be unique to support name-based reflection of ")
				TEXT("shader source files."),
				ShaderVariableName,
				StructTypeName,
				*StructFName->GetPlainNameString());
		}

		GetGlobalShaderVariableToStructMap().Add(ShaderVariableFName, StructTypeFName);
#endif
	}
	else
	{
		// We cannot initialize the layout during global initialization, since we have to walk nested struct members.
		// Structs created during global initialization will have bRegisterForAutoBinding==false, and are initialized during startup.
		// Structs created at runtime with bRegisterForAutoBinding==true can be initialized now.
		InitializeLayout(OutLayoutInitializer);
	}
}

FShaderParametersMetadata::~FShaderParametersMetadata()
{
	// FShaderParametersMetadata are objects at file scope
	//	this destructor can run at process exit
	// it touches globals like GlobalShaderVariableToStructMap and GLayoutHashStructMap
	//	must ensure they are not already be destructed

	if (GlobalListLink.IsLinked())
	{
		check(UseCase == EUseCase::UniformBuffer);
		GlobalListLink.Unlink();
		GetNameStructMap().Remove(ShaderVariableHashedName);

#if VALIDATE_UNIFORM_BUFFER_UNIQUE_NAME
		GetGlobalShaderVariableToStructMap().Remove(FName(ShaderVariableName, FNAME_Find));
#endif

		if (IsLayoutInitialized())
		{
			GetLayoutHashStructMap().Remove(GetLayout().GetHash());
		}
	}
}


void FShaderParametersMetadata::InitializeAllUniformBufferStructs()
{
	for (TLinkedList<FShaderParametersMetadata*>::TIterator StructIt(FShaderParametersMetadata::GetStructList()); StructIt; StructIt.Next())
	{
		if (!StructIt->IsLayoutInitialized())
		{
			StructIt->InitializeLayout();
		}
	}
}

void FShaderParametersMetadata::InitializeLayout(FRHIUniformBufferLayoutInitializer* OutLayoutInitializer)
{
	check(!IsLayoutInitialized());

	FRHIUniformBufferLayoutInitializer LocalLayoutInitializer(LayoutName);
	FRHIUniformBufferLayoutInitializer& LayoutInitializer = OutLayoutInitializer ? *OutLayoutInitializer : LocalLayoutInitializer;
	LayoutInitializer.ConstantBufferSize = Size;
	LayoutInitializer.bNoEmulatedUniformBuffer = UsageFlags & (uint32)EUsageFlags::NoEmulatedUniformBuffer;

	if (StaticSlotName)
	{
		checkf(EnumHasAnyFlags(BindingFlags, EUniformBufferBindingFlags::Static), TEXT("Uniform buffer of type '%s' and shader name '%s' attempted to reference static slot '%s', but the binding model does not contain 'Global'."),
			StructTypeName, ShaderVariableName, StaticSlotName);

		checkf(UseCase == EUseCase::UniformBuffer,
			TEXT("Attempted to assign static slot %s to uniform buffer %s. Static slots are only supported for compile-time uniform buffers."),
			ShaderVariableName, StaticSlotName);

		const FUniformBufferStaticSlot StaticSlot = FUniformBufferStaticSlotRegistry::Get().FindSlotByName(StaticSlotName);

		checkf(IsUniformBufferStaticSlotValid(StaticSlot),
			TEXT("Uniform buffer of type '%s' and shader name '%s' attempted to reference static slot '%s', but the slot could not be found in the registry."),
			StructTypeName, ShaderVariableName, StaticSlotName);

		LayoutInitializer.StaticSlot = StaticSlot;
		LayoutInitializer.BindingFlags = BindingFlags;
	}
	else
	{
		checkf(!EnumHasAnyFlags(BindingFlags, EUniformBufferBindingFlags::Static), TEXT("Uniform buffer of type '%s' and shader name '%s' has no binding slot specified, but the binding model specifies 'Global'."),
			StructTypeName, ShaderVariableName, StaticSlotName);
	}

	TArray<FUniformBufferMemberAndOffset> MemberStack;
	MemberStack.Reserve(Members.Num());
	for (int32 MemberIndex = 0; MemberIndex < Members.Num(); MemberIndex++)
	{
		MemberStack.Push(FUniformBufferMemberAndOffset(*this, Members[MemberIndex], 0));
	}

	/** Uniform buffer references are only allowed in shader parameter structures that may be used as a root shader parameter
	 * structure.
	 */
	const bool bAllowUniformBufferReferences = UseCase == EUseCase::ShaderParameterStruct;

	/** Resource array are currently only supported for shader parameter structures. */
	const bool bAllowResourceArrays = UseCase == EUseCase::ShaderParameterStruct;

	/** Allow all use cases that inline a structure within another. Data driven are not known to inline structures. */
	const bool bAllowStructureInlining = UseCase == EUseCase::ShaderParameterStruct || UseCase == EUseCase::UniformBuffer;

	for (int32 i = 0; i < MemberStack.Num(); ++i)
	{
		const FShaderParametersMetadata& CurrentStruct = MemberStack[i].ContainingStruct;
		const FMember& CurrentMember = MemberStack[i].Member;

		EUniformBufferBaseType BaseType = CurrentMember.GetBaseType();
		const uint32 ArraySize = CurrentMember.GetNumElements();
		const FShaderParametersMetadata* ChildStruct = CurrentMember.GetStructMetadata();
		const TCHAR* ShaderType = CurrentMember.GetShaderType();

		const bool bIsArray = ArraySize > 0;
		const bool bIsRHIResource = (
			BaseType == UBMT_TEXTURE ||
			BaseType == UBMT_SRV ||
			BaseType == UBMT_SAMPLER);
		const bool bIsRDGResource = IsRDGResourceReferenceShaderParameterType(BaseType);
		const bool bIsVariableNativeType = (
			BaseType == UBMT_INT32 ||
			BaseType == UBMT_UINT32 ||
			BaseType == UBMT_FLOAT32);

		LayoutInitializer.bHasNonGraphOutputs |= BaseType == UBMT_UAV;

		if (DO_CHECK)
		{
			auto GetMemberErrorPrefix = [&]()
			{
				return FString::Printf(
					TEXT("%s(%i): Shader parameter %s::%s error:\n"),
					ANSI_TO_TCHAR(CurrentStruct.GetFileName()),
					CurrentMember.GetFileLine(),
					CurrentStruct.GetStructTypeName(),
					CurrentMember.GetName());
			};

			if (BaseType == UBMT_BOOL)
			{
				UE_LOG(LogRendererCore, Fatal,
					TEXT("%sbool are actually illegal in shader parameter structure, ")
					TEXT("because bool type in HLSL means using scalar register to store binary information. ")
					TEXT("Boolean information should always be packed explicitly in bitfield to reduce memory footprint, ")
					TEXT("and use HLSL comparison operators to translate into clean SGPR, to have minimal VGPR footprint."), *GetMemberErrorPrefix());
			}

			if (BaseType == UBMT_REFERENCED_STRUCT || BaseType == UBMT_RDG_UNIFORM_BUFFER)
			{
				check(ChildStruct);

				if (!bAllowUniformBufferReferences)
				{
					UE_LOG(LogRendererCore, Fatal, TEXT("%sShader parameter struct reference can only be done in shader parameter structs."), *GetMemberErrorPrefix());
				}
			}
			else if (BaseType == UBMT_NESTED_STRUCT || BaseType == UBMT_INCLUDED_STRUCT)
			{
				check(ChildStruct);

				if (!bAllowStructureInlining)
				{
					UE_LOG(LogRendererCore, Fatal, TEXT("%sShader parameter struct is not known inline other structures."), *GetMemberErrorPrefix());
				}
				else if (ChildStruct->GetUseCase() != EUseCase::ShaderParameterStruct && UseCase == EUseCase::ShaderParameterStruct)
				{
					UE_LOG(LogRendererCore, Fatal, TEXT("%sCan only nests or include shader parameter struct define with BEGIN_SHADER_PARAMETER_STRUCT(), but %s is not."), *GetMemberErrorPrefix(), ChildStruct->GetStructTypeName());
				}
			}

			if (UseCase != EUseCase::ShaderParameterStruct && IsShaderParameterTypeIgnoredByRHI(BaseType))
			{
				UE_LOG(LogRendererCore, Fatal, TEXT("Shader parameter %s is not allowed in a uniform buffer."), *GetMemberErrorPrefix());
			}

			const bool bTypeCanBeArray = (bAllowResourceArrays && (bIsRHIResource || bIsRDGResource)) || bIsVariableNativeType || BaseType == UBMT_NESTED_STRUCT;
			if (bIsArray && !bTypeCanBeArray)
			{
				UE_LOG(LogRendererCore, Fatal, TEXT("%sNot allowed to be an array."), *GetMemberErrorPrefix());
			}

			// Validate the shader binding type.
			if (bIsRHIResource || (bIsRDGResource && !IsRDGResourceAccessType(BaseType) && BaseType != UBMT_RDG_UNIFORM_BUFFER))
			{
				EShaderCodeResourceBindingType BindingType = ParseShaderResourceBindingType(ShaderType);

				if (BindingType == EShaderCodeResourceBindingType::Invalid)
				{
					UE_LOG(LogRendererCore, Warning, TEXT("%sUnknown shader parameter type %s."), *GetMemberErrorPrefix(), ShaderType);
				}

				bool bIsValidBindingType = false;
				if (BindingType == EShaderCodeResourceBindingType::SamplerState)
				{
					bIsValidBindingType = (BaseType == UBMT_SAMPLER);
				}
				else if (
					BindingType == EShaderCodeResourceBindingType::Texture2D ||
					BindingType == EShaderCodeResourceBindingType::Texture2DArray ||
					BindingType == EShaderCodeResourceBindingType::Texture2DMS ||
					BindingType == EShaderCodeResourceBindingType::Texture3D ||
					BindingType == EShaderCodeResourceBindingType::TextureCube ||
					BindingType == EShaderCodeResourceBindingType::TextureCubeArray)
				{
					bIsValidBindingType = (
						BaseType == UBMT_TEXTURE ||
						BaseType == UBMT_SRV ||
						BaseType == UBMT_RDG_TEXTURE ||
						BaseType == UBMT_RDG_TEXTURE_SRV);
				}
				else if (BindingType == EShaderCodeResourceBindingType::TextureMetadata)
				{
					bIsValidBindingType = (
						BaseType == UBMT_SRV ||
						BaseType == UBMT_RDG_TEXTURE_SRV);
				}
				else if (
					BindingType == EShaderCodeResourceBindingType::Buffer ||
					BindingType == EShaderCodeResourceBindingType::StructuredBuffer ||
					BindingType == EShaderCodeResourceBindingType::ByteAddressBuffer)
				{
					bIsValidBindingType = (
						BaseType == UBMT_SRV ||
						BaseType == UBMT_RDG_BUFFER_SRV);
				}
				else if (BindingType == EShaderCodeResourceBindingType::RaytracingAccelerationStructure)
				{
					bIsValidBindingType = (
						BaseType == UBMT_SRV ||
						BaseType == UBMT_RDG_BUFFER_SRV);
				}
				else if (
					BindingType == EShaderCodeResourceBindingType::RWTexture2D ||
					BindingType == EShaderCodeResourceBindingType::RWTexture2DArray ||
					BindingType == EShaderCodeResourceBindingType::RWTexture3D ||
					BindingType == EShaderCodeResourceBindingType::RWTextureCube ||
					BindingType == EShaderCodeResourceBindingType::RWTextureMetadata ||
					BindingType == EShaderCodeResourceBindingType::RasterizerOrderedTexture2D)
				{
					bIsValidBindingType = (
						BaseType == UBMT_UAV ||
						BaseType == UBMT_RDG_TEXTURE_UAV);
				}
				else if (
					BindingType == EShaderCodeResourceBindingType::RWBuffer ||
					BindingType == EShaderCodeResourceBindingType::RWStructuredBuffer ||
					BindingType == EShaderCodeResourceBindingType::RWByteAddressBuffer)
				{
					bIsValidBindingType = (
						BaseType == UBMT_UAV ||
						BaseType == UBMT_RDG_BUFFER_UAV);
				}
				else
				{
					//unimplemented();
				}

				if (!bIsValidBindingType)
				{
					const TCHAR* CurrentMacroName = GetShaderParameterMacroName(BaseType);
					UE_LOG(
						LogRendererCore, Warning,
						TEXT("%sUnable to bind a shader parameter type %s with a %s."),
						*GetMemberErrorPrefix(), ShaderType, CurrentMacroName);
				}
			}
		}

		if (IsShaderParameterTypeForUniformBufferLayout(BaseType))
		{
			for (uint32 ArrayElementId = 0; ArrayElementId < (bIsArray ? ArraySize : 1u); ArrayElementId++)
			{
				const uint32 AbsoluteMemberOffset = CurrentMember.GetOffset() + MemberStack[i].StructOffset + ArrayElementId * SHADER_PARAMETER_POINTER_ALIGNMENT;
				check(AbsoluteMemberOffset < (1u << (sizeof(FRHIUniformBufferResource::MemberOffset) * 8)));
				const FRHIUniformBufferResource ResourceParameter{ uint16(AbsoluteMemberOffset), BaseType };

				LayoutInitializer.Resources.Add(ResourceParameter);

				if (IsRDGTextureReferenceShaderParameterType(BaseType) || BaseType == UBMT_RENDER_TARGET_BINDING_SLOTS)
				{
					LayoutInitializer.GraphResources.Add(ResourceParameter);
					LayoutInitializer.GraphTextures.Add(ResourceParameter);

					if (BaseType == UBMT_RENDER_TARGET_BINDING_SLOTS)
					{
						checkf(!LayoutInitializer.HasRenderTargets(), TEXT("Shader parameter struct %s has multiple render target binding slots."), GetStructTypeName());
						LayoutInitializer.RenderTargetsOffset = ResourceParameter.MemberOffset;
					}
				}
				else if (IsRDGBufferReferenceShaderParameterType(BaseType))
				{
					LayoutInitializer.GraphResources.Add(ResourceParameter);
					LayoutInitializer.GraphBuffers.Add(ResourceParameter);
				}
				else if (BaseType == UBMT_RDG_UNIFORM_BUFFER)
				{
					LayoutInitializer.GraphResources.Add(ResourceParameter);
					LayoutInitializer.GraphUniformBuffers.Add(ResourceParameter);
				}
				else if (BaseType == UBMT_REFERENCED_STRUCT)
				{
					LayoutInitializer.UniformBuffers.Add(ResourceParameter);
				}
			}
		}

		if (ChildStruct && BaseType != UBMT_REFERENCED_STRUCT && BaseType != UBMT_RDG_UNIFORM_BUFFER)
		{
			for (uint32 ArrayElementId = 0; ArrayElementId < (bIsArray ? ArraySize : 1u); ArrayElementId++)
			{
				int32 AbsoluteStructOffset = CurrentMember.GetOffset() + MemberStack[i].StructOffset + ArrayElementId * ChildStruct->GetSize();

				for (int32 StructMemberIndex = 0; StructMemberIndex < ChildStruct->Members.Num(); StructMemberIndex++)
				{
					const FMember& StructMember = ChildStruct->Members[StructMemberIndex];
					MemberStack.Insert(FUniformBufferMemberAndOffset(*ChildStruct, StructMember, AbsoluteStructOffset), i + 1 + StructMemberIndex);
				}
			}
		}
	}

	const auto ByMemberOffset = [](
		const FRHIUniformBufferResource& A,
		const FRHIUniformBufferResource& B)
	{
		return A.MemberOffset < B.MemberOffset;
	};

	const auto ByTypeThenMemberOffset = [](
		const FRHIUniformBufferResource& A,
		const FRHIUniformBufferResource& B)
	{
		if (A.MemberType == B.MemberType)
		{
			return A.MemberOffset < B.MemberOffset;
		}
		return A.MemberType < B.MemberType;
	};

	LayoutInitializer.Resources.Sort(ByMemberOffset);
	LayoutInitializer.GraphResources.Sort(ByMemberOffset);
	LayoutInitializer.GraphTextures.Sort(ByTypeThenMemberOffset);
	LayoutInitializer.GraphBuffers.Sort(ByTypeThenMemberOffset);
	LayoutInitializer.GraphUniformBuffers.Sort(ByMemberOffset);
	LayoutInitializer.UniformBuffers.Sort(ByMemberOffset);

	// Compute the hash of the RHI layout.
	LayoutInitializer.ComputeHash();
	
	// Compute the hash about the entire layout of the structure.
	{
		uint32 RootStructureHash = 0;
		RootStructureHash = HashCombine(RootStructureHash, GetTypeHash(int32(GetSize())));

		for (const FMember& CurrentMember : Members)
		{
			EUniformBufferBaseType BaseType = CurrentMember.GetBaseType();
			const FShaderParametersMetadata* ChildStruct = CurrentMember.GetStructMetadata();

			uint32 MemberHash = 0;
			MemberHash = HashCombine(MemberHash, GetTypeHash(int32(CurrentMember.GetOffset())));
			MemberHash = HashCombine(MemberHash, GetTypeHash(uint8(BaseType)));
			static_assert(EUniformBufferBaseType_NumBits <= 8, "Invalid EUniformBufferBaseType_NumBits");
			MemberHash = HashCombine(MemberHash, GetTypeHash(CurrentMember.GetName()));
			MemberHash = HashCombine(MemberHash, GetTypeHash(int32(CurrentMember.GetNumElements())));

			const bool bIsRHIResource = (
				BaseType == UBMT_TEXTURE ||
				BaseType == UBMT_SRV ||
				BaseType == UBMT_SAMPLER);
			const bool bIsRDGResource = IsRDGResourceReferenceShaderParameterType(BaseType);

			if (BaseType == UBMT_INT32 ||
				BaseType == UBMT_UINT32 ||
				BaseType == UBMT_FLOAT32)
			{
				MemberHash = HashCombine(MemberHash, GetTypeHash(uint8(CurrentMember.GetNumRows())));
				MemberHash = HashCombine(MemberHash, GetTypeHash(uint8(CurrentMember.GetNumColumns())));
			}
			else if (BaseType == UBMT_INCLUDED_STRUCT || BaseType == UBMT_NESTED_STRUCT)
			{
				if (!ChildStruct->IsLayoutInitialized())
				{
					const_cast<FShaderParametersMetadata*>(ChildStruct)->InitializeLayout();
				}

				MemberHash = HashCombine(MemberHash, ChildStruct->GetLayoutHash());
			}
			else if (bIsRHIResource || bIsRDGResource)
			{
				MemberHash = HashCombine(MemberHash, GetTypeHash(CurrentMember.GetShaderType()));
			}

			RootStructureHash = HashCombine(RootStructureHash, MemberHash);
		}

		LayoutHash = RootStructureHash;
	}

	if (UseCase == EUseCase::UniformBuffer)
	{
		GetLayoutHashStructMap().Emplace(LayoutInitializer.GetHash(), this);
	}

	Layout = new FRHIUniformBufferLayout(LayoutInitializer);
}

void FShaderParametersMetadata::GetNestedStructs(TArray<const FShaderParametersMetadata*>& OutNestedStructs) const
{
	for (int32 i = 0; i < Members.Num(); ++i)
	{
		const FMember& CurrentMember = Members[i];

		const FShaderParametersMetadata* MemberStruct = CurrentMember.GetStructMetadata();

		if (MemberStruct)
		{
			OutNestedStructs.Add(MemberStruct);
			MemberStruct->GetNestedStructs(OutNestedStructs);
		}
	}
}

void FShaderParametersMetadata::AddResourceTableEntries(TMap<FString, FResourceTableEntry>& ResourceTableMap, TMap<FString, FUniformBufferEntry>& UniformBufferMap) const
{
	uint16 ResourceIndex = 0;
	FString Prefix = FString::Printf(TEXT("%s_"), ShaderVariableName);
	AddResourceTableEntriesRecursive(ShaderVariableName, *Prefix, ResourceIndex, ResourceTableMap);
	
	FUniformBufferEntry UniformBufferEntry;
	UniformBufferEntry.StaticSlotName = StaticSlotName;
	UniformBufferEntry.LayoutHash = IsLayoutInitialized() ? GetLayout().GetHash() : 0;
	UniformBufferEntry.BindingFlags = BindingFlags;
	UniformBufferEntry.bNoEmulatedUniformBuffer = UsageFlags & (uint32)EUsageFlags::NoEmulatedUniformBuffer;
	UniformBufferMap.Add(ShaderVariableName, UniformBufferEntry);
}

void FShaderParametersMetadata::AddResourceTableEntriesRecursive(const TCHAR* UniformBufferName, const TCHAR* Prefix, uint16& ResourceIndex, TMap<FString, FResourceTableEntry>& ResourceTableMap) const
{
	for (int32 MemberIndex = 0; MemberIndex < Members.Num(); ++MemberIndex)
	{
		const FMember& Member = Members[MemberIndex];
		uint32 NumElements = Member.GetNumElements();

		if (IsShaderParameterTypeForUniformBufferLayout(Member.GetBaseType()))
		{
			FResourceTableEntry& Entry = ResourceTableMap.FindOrAdd(FString::Printf(TEXT("%s%s"), Prefix, Member.GetName()));
			if (Entry.UniformBufferName.IsEmpty())
			{
				Entry.UniformBufferName = UniformBufferName;
				Entry.Type = Member.GetBaseType();
				Entry.ResourceIndex = ResourceIndex++;
			}
		}
		else if (Member.GetBaseType() == UBMT_NESTED_STRUCT && NumElements == 0)
		{
			check(Member.GetStructMetadata());
			FString MemberPrefix = FString::Printf(TEXT("%s%s_"), Prefix, Member.GetName());
			Member.GetStructMetadata()->AddResourceTableEntriesRecursive(UniformBufferName, *MemberPrefix, ResourceIndex, ResourceTableMap);
		}
		else if (Member.GetBaseType() == UBMT_NESTED_STRUCT && NumElements > 0)
		{
			for (uint32 ArrayElementId = 0; ArrayElementId < NumElements; ArrayElementId++)
			{
				check(Member.GetStructMetadata());
				FString MemberPrefix = FString::Printf(TEXT("%s%s_%u_"), Prefix, Member.GetName(), ArrayElementId);
				Member.GetStructMetadata()->AddResourceTableEntriesRecursive(UniformBufferName, *MemberPrefix, ResourceIndex, ResourceTableMap);
			}
		}
		else if (Member.GetBaseType() == UBMT_INCLUDED_STRUCT)
		{
			check(Member.GetStructMetadata());
			check(NumElements == 0);
			Member.GetStructMetadata()->AddResourceTableEntriesRecursive(UniformBufferName, Prefix, ResourceIndex, ResourceTableMap);
		}
	}
}

void FShaderParametersMetadata::FindMemberFromOffset(uint16 MemberOffset, const FShaderParametersMetadata** OutContainingStruct, const FShaderParametersMetadata::FMember** OutMember, int32* ArrayElementId, FString* NamePrefix) const
{
	check(MemberOffset < GetSize());

	for (const FMember& Member : Members)
	{
		EUniformBufferBaseType BaseType = Member.GetBaseType();
		uint32 NumElements = Member.GetNumElements();

		if ((BaseType == UBMT_NESTED_STRUCT && NumElements == 0) || BaseType == UBMT_INCLUDED_STRUCT)
		{
			const FShaderParametersMetadata* SubStruct = Member.GetStructMetadata();
			if (MemberOffset < (Member.GetOffset() + SubStruct->GetSize()))
			{
				if (NamePrefix)
				{
					*NamePrefix = FString::Printf(TEXT("%s%s::"), **NamePrefix, Member.GetName());
				}

				return SubStruct->FindMemberFromOffset(MemberOffset - Member.GetOffset(), OutContainingStruct, OutMember, ArrayElementId, NamePrefix);
			}
		}
		else if (BaseType == UBMT_NESTED_STRUCT && NumElements > 0)
		{
			const FShaderParametersMetadata* SubStruct = Member.GetStructMetadata();
			uint32 StructSize = SubStruct->GetSize();
			
			uint16 ArrayStartOffset = Member.GetOffset();
			uint16 ArrayEndOffset = ArrayStartOffset + SubStruct->GetSize() * NumElements;
			
			if (MemberOffset >= ArrayStartOffset && MemberOffset < ArrayEndOffset)
			{
				uint32 MemberOffsetInArray = MemberOffset - ArrayStartOffset;
				check((MemberOffsetInArray % StructSize) == 0);

				uint32 MemberPosInStructArray = MemberOffsetInArray / StructSize;
				uint32 MemberOffsetInStructElement = MemberOffsetInArray - MemberPosInStructArray * StructSize;

				if (NamePrefix)
				{
					*NamePrefix = FString::Printf(TEXT("%s%s[%u]::"), **NamePrefix, Member.GetName(), MemberPosInStructArray);
				}

				return SubStruct->FindMemberFromOffset(MemberOffsetInStructElement, OutContainingStruct, OutMember, ArrayElementId, NamePrefix);
			}
		}
		else if (NumElements > 0 && (
			BaseType == UBMT_TEXTURE ||
			BaseType == UBMT_SRV ||
			BaseType == UBMT_SAMPLER ||
			IsRDGResourceReferenceShaderParameterType(BaseType)))
		{
			uint16 ArrayStartOffset = Member.GetOffset();
			uint16 ArrayEndOffset = ArrayStartOffset + SHADER_PARAMETER_POINTER_ALIGNMENT * NumElements;

			if (MemberOffset >= ArrayStartOffset && MemberOffset < ArrayEndOffset)
			{
				check((MemberOffset % SHADER_PARAMETER_POINTER_ALIGNMENT) == 0);
				*OutContainingStruct = this;
				*OutMember = &Member;
				*ArrayElementId = (MemberOffset - ArrayStartOffset) / SHADER_PARAMETER_POINTER_ALIGNMENT;
				return;
			}
		}
		else if (Member.GetOffset() == MemberOffset)
		{
			*OutContainingStruct = this;
			*OutMember = &Member;
			*ArrayElementId = 0;
			return;
		}
	}

	checkf(0, TEXT("Looks like this offset is invalid."));
}

FString FShaderParametersMetadata::GetFullMemberCodeName(uint16 MemberOffset) const
{
	const FShaderParametersMetadata* MemberContainingStruct = nullptr;
	const FShaderParametersMetadata::FMember* Member = nullptr;
	int32 ArrayElementId = 0;
	FString NamePrefix;
	FindMemberFromOffset(MemberOffset, &MemberContainingStruct, &Member, &ArrayElementId, &NamePrefix);

	FString MemberName = FString::Printf(TEXT("%s%s"), *NamePrefix, Member->GetName());
	if (Member->GetNumElements() > 0)
	{
		MemberName = FString::Printf(TEXT("%s%s[%d]"), *NamePrefix, Member->GetName(), ArrayElementId);
	}

	return MemberName;
}